The present invention relates to status indication in communication devices.
Many communication devices, such as cellular telephones, employ a simple status indicator, in addition to large multi-pixel displays, to communicate information to a user of the cellular telephone. One cellular telephone employs a single light emitting diode (LED) device that flashes red when the cellular telephone receives incoming calls or incoming messages. Another cellular telephone uses a single multi-color LED device that alternates flashing red and green when the cellular telephone receives an incoming call, but does not flash when the cellular telephone receives incoming messages. When a call is not incoming, occurring or being placed, the multi-color LED device is controlled to visually indicate the operating status of the cellular telephone. The multi-color LED device flashes red when the cellular telephone has no service (i.e., the cellular telephone is beyond the range of a cellular service area and calls on the cellular telephone cannot be received or placed), flashes green when the cellular telephone is in-service (i.e., the cellular telephone is in communication with a cellular system and calls on the cellular telephone can be received or placed) and flashes yellow when the cellular telephone is roaming (i.e., the cellular telephone is accessing cellular service outside of the cellular telephone""s home system).
A prior art scheme 500 for controlling a status indicator 501 to visually indicate, for example, in-service status, is shown in FIG. 5. The scheme 501 is characterized by continuous, repetitive indication periods, of which indication period 502 is exemplary. The indication period 502 has a single pulse 504, whose width corresponds to the time period that the status indicator 501 is powered-on to emit the color green corresponding to the in-service status. A user will visually perceive that the status indicator 501 flashes the color green because the pulse 504 is separated from pulse 505 of a following indication period 503 by a suitable pulse separator 506 of the indication period 502. The length of the pulse separator 506 corresponds to the time period during the indication period 502 that the status indicator 501 is powered-off. During the indication period 502, the status indicator 501 is powered-on for 500 ms and powered off for 1500 ms. As can be seen, the status indicator 501 of the prior art scheme 500 is controlled to only provide a visual indication of one type of status information (i.e., in-service status) per indication period. Also, because the cellular telephone will spend the majority of its powered-on time indicating in-service status while waiting for a call to be received or placed, the status indicator 501, as controlled according to the scheme 500, exacts a high current drain of approximately 2 mA for each indication period.
Therefore, what is needed is a method of controlling a status indicator to visually indicate a plurality of status information. The method should be conducive to minimizing current drain and optimizing usability of the status indicator.